[P3Se4]+: A Binary Phosphorus Selenium Cation

Pseudohalogen Chemistry in Ionic Liquids with Non-innocent Cations and Anions

Within the second funding period of the SPP 1708 "Material Synthesis near Room Temperature",which started in 2017, we were able to synthesize novel anionic species utilizing Ionic Liquids (ILs) both, as reaction media and reactant. ILs, bearing the decomposable and non-innocent methyl carbonate anion [CO3 Me]- , served as starting material and enabled facile access to pseudohalide salts by reaction with Me3 Si-X (X=CN, N3 , OCN, SCN). Starting with the synthesized Room temperature Ionic Liquid (RT-IL) [nBu3 MeN][B(OMe)3 (CN)], we were able to crystallize the double salt [nBu3 MeN]2 [B(OMe)3 (CN)](CN). Furthermore, we studied the reaction of [WCC]SCN and [WCC]CN (WCC=weakly coordinating cation) with their corresponding protic acids HX (X=SCN, CN), which resulted in formation of [H(NCS)2 ]- and the temperature labile solvate anions [CN(HCN)n ]- (n=2, 3). In addition, the highly labile anionic HCN solvates were obtained from [PPN]X ([PPN]=μ-nitridobis(triphenylphosphonium), X=N3 , OCN, SCN and OCP) and HCN. Crystals of [PPN][X(HCN)3 ] (X=N3 , OCN) and [PPN][SCN(HCN)2 ] were obtained when the crystallization was carried out at low temperatures. Interestingly, reaction of [PPN]OCP with HCN was noticed, which led to the formation of [P(CN)2 ]- , crystallizing as HCN disolvate [PPN][P(CN⋅HCN)2 ]. Furthermore, we were able to isolate the novel cyanido(halido) silicate dianions of the type [SiCl0.78 (CN)5.22 ]2- and [SiF(CN)5 ]2- and the hexa-substituted [Si(CN)6 ]2- by temperature controlled halide/cyanide exchange reactions. By facile neutralization reactions with the non-innocent cation of [Et3 HN]2 [Si(CN)6 ] with MOH (M=Li, K), Li2 [Si(CN)6 ] ⋅ 2 H2 O and K2 [Si(CN)6 ] were obtained, which form three dimensional coordination polymers. From salt metathesis processes of M2 [Si(CN)6 ] with different imidazolium bromides, we were able to isolate new imidazolium salts and the ionic liquid [BMIm]2 [Si(CN)6 ]. When reacting [Mes(nBu)Im]2 [Si(CN)6 ] with an excess of the strong Lewis acid B(C6 F5 )3 , the voluminous adduct anion {Si[CN⋅B(C6 F5 )3 ]6 }2- was obtained.

Reactive p-block cations stabilized by weakly coordinating anions

The chemistry of the p-block elements is a huge playground for fundamental and applied work. With their bonding from electron deficient to hypercoordinate and formally hypervalent, the p-block elements represent an area to find terra incognita. Often, the formation of cations that contain p-block elements as central ingredient is desired, for example to make a compound more Lewis acidic for an application or simply to prove an idea. This review has collected the reactive p-block cations (rPBC) with a comprehensive focus on those that have been published since the year 2000, but including the milestones and key citations of earlier work. We include an overview on the weakly coordinating anions (WCAs) used to stabilize the rPBC and give an overview to WCA selection, ionization strategies for rPBC-formation and finally list the rPBC ordered in their respective group from 13 to 18. However, typical, often more organic ion classes that constitute for example ionic liquids (imidazolium, ammonium, etc.) were omitted, as were those that do not fulfill the - naturally subjective -"reactive"-criterion of the rPBC. As a rule, we only included rPBC with crystal structure and only rarely refer to important cations published without crystal structure. This collection is intended for those who are simply interested what has been done or what is possible, as well as those who seek advice on preparative issues, up to people having a certain application in mind, where the knowledge on the existence of a rPBC that might play a role as an intermediate or active center may be useful.